Joshua Ramette | Courtesy

In the largest project ever funded by the National Science Foun­dation, sci­en­tists have found evi­dence con­firming Albert Einstein’s theory of general rel­a­tivity. Among the hun­dreds of col­lab­o­rators is junior Joshua Ramette, whose research over the summer con­tributed to the first-ever detection of grav­i­ta­tional waves.

The Laser Inter­fer­ometer Grav­i­ta­tional-Wave Obser­vatory, or LIGO, uses a high-powered laser beam reflected across a series of mirrors to detect grav­i­ta­tional waves, a phe­nomenon pre­dicted in Einstein’s work. The merging of black holes located bil­lions of light years away from the Earth pro­duced grav­i­ta­tional waves, which cause cause tiny dis­tor­tions in space. Until now, these waves were not observable. LIGO sci­en­tists observed the first grav­i­ta­tional waves Sept. 14, 2015 and pub­li­cized their findings Feb. 11 in a press con­ference.

The promise of working on what Ramette called “one of the premier physics exper­i­ments in the world” spurred him to apply for the summer internship.

“It’s very inter­esting because it’s an exper­iment you can do with general rel­a­tivity, so it relates to some of the most fun­da­mental physics we can grasp right now,” Ramette said.

The main laser beam travels through a prism, splitting the beam in two. These off­shoots travel down two four-kilo­meter tubes, reflecting across a series of finely tuned of mirrors and into a sensor. When a grav­i­ta­tional wave passes through the earth, the space inside the tubes is dis­torted, altering the pattern that the laser creates on the sensor. Each mirror is care­fully sus­pended to isolate the system from the seis­mo­logical activity of the earth.

In order to obtain accurate mea­sure­ments, the system’s mirrors must care­fully be cal­i­brated so as not to distort the laser’s path.

“The high power main laser beam heats the mirrors upon reflection, causing problems for the optics,” Ramette said.

Over the summer, Ramette worked with a team at the LIGO Liv­ingston Obser­vatory in Louisiana to help correct the tem­per­ature of the mirrors using a device called a ring heater to stan­dardize the tem­per­ature throughout each mirror. In order to do this, Ramette modeled the heating pat­terns from the ring heater using math­e­matical equa­tions and com­puter software. Then, the team com­pared the models to the actual tem­per­ature readings in the mirrors.

Their project built on the research of two sci­en­tists in the 1990s, who worked out the math­e­matics behind the prob­lematic tem­per­ature change caused by the laser beam. Working off their data, Ramette and the others created and tested the models nec­essary to sta­bilize the mirror tem­per­a­tures and increase LIGO sen­si­tivity.

“They figured out how the heating from the main laser beam works,” he said. “I figured out how the ring heater works.”

Ramette has sub­mitted the work to the journal “Applied Optics” and is cur­rently in the process of pub­lishing a paper.

The extremely sen­sitive LIGO instru­ments cur­rently are only able to detect large grav­i­ta­tional waves, but Pro­fessor of Physics Ken Hayes said future work may allow for the detection of smaller grav­i­ta­tional waves.

“The tech­nology of LIGO is astounding,” he said.

David Reitze, LIGO Lab­o­ratory Exec­utive Director, called LIGO’s detection of grav­i­ta­tional waves one of the largest advance­ments in physics since Galileo first pointed his tele­scope toward the stars.

“This is not just about the detection of grav­i­ta­tional waves,” he said at the press con­ference. “That’s the story today, but what’s really exciting is what comes next. I think we’re opening a window on the uni­verse — a window of grav­i­ta­tional wave astronomy.”